Introduce "bytes_string" type, similar to "value_string"

In order to map arbitrary byte buffers to strings, introduce a new
"bytes_string" type. Since "bytes_to_str" is already used for other
purposes, name the generic function "bytesval_to_str" instead similar to
the name( "val_to_str").

Accept "size_t" as length parameter since this is what is returned by
the "sizeof" operator. Do not add a "try_bytesval_to_str_idx" variant
since this pattern is not needed for now. Add a variant to match the
prefix since this is currently expected by the ISAKMP dissector.

Change-Id: I6d790325e85d9fb1384330f28a8c36e2057fdf30
Reviewed-on: https://code.wireshark.org/review/20386
Petri-Dish: Alexis La Goutte <alexis.lagoutte@gmail.com>
Tested-by: Petri Dish Buildbot <buildbot-no-reply@wireshark.org>
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>
Reviewed-by: Peter Wu <peter@lekensteyn.nl>

4 files changed, 109 insertions, 55 deletions

diff --git a/debian/libwireshark0.symbols b/debian/libwireshark0.symbols
index ed43473c56..b9525096e4 100644
--- a/debian/libwireshark0.symbols
+++ b/debian/libwireshark0.symbols
@@ -76,6 +76,8 @@ libwireshark.so.0 libwireshark0 #MINVER#
  byte_array_equal@Base 1.9.1
  bytes_to_hexstr@Base 2.1.0
  bytes_to_str@Base 1.99.2
+ bytesprefix_to_str@Base 2.3.0
+ bytesval_to_str@Base 2.3.0
  bytestring_to_str@Base 1.9.1
  call_ber_oid_callback@Base 1.9.1
  call_capture_dissector@Base 2.3.0
@@ -1507,6 +1509,8 @@ libwireshark.so.0 libwireshark0 #MINVER#
  tree_expanded@Base 1.12.0~rc1
  tree_expanded_set@Base 1.12.0~rc1
  try_capture_dissector@Base 2.1.0
+ try_bytesprefix_to_str@Base 2.3.0
+ try_bytesval_to_str@Base 2.3.0
  try_rval_to_str@Base 1.9.1
  try_rval_to_str_idx@Base 1.9.1
  try_rval64_to_str@Base 2.3.0
diff --git a/epan/dissectors/packet-isakmp.c b/epan/dissectors/packet-isakmp.c
index d324d447fa..25bb1427bf 100644
--- a/epan/dissectors/packet-isakmp.c
+++ b/epan/dissectors/packet-isakmp.c
@@ -72,14 +72,6 @@
 void proto_register_isakmp(void);
 void proto_reg_handoff_isakmp(void);
 
-/* Struct for the byte_to_str, match_bytestr_idx, and match_bytestr functions */
-
-typedef struct _byte_string {
-  const gchar   *value;
-  const guint16 len;
-  const gchar   *strptr;
-} byte_string;
-
 typedef struct _attribute_common_fields {
   int all;
   int format;
@@ -2826,8 +2818,7 @@ static const guint8 VID_FORTINET_ENDPOINT_CONTROL[] = { /* Endpoint Control (For
         0x0B, 0xAF, 0xBB, 0xD3, 0x4A, 0xD3, 0x04, 0x4E
 };
 
-/* Based from value_string.c/h */
-static const byte_string vendor_id[] = {
+static const bytes_string vendor_id[] = {
   { VID_SSH_IPSEC_EXPRESS_1_1_0, sizeof(VID_SSH_IPSEC_EXPRESS_1_1_0), "Ssh Communications Security IPSEC Express version 1.1.0" },
   { VID_SSH_IPSEC_EXPRESS_1_1_1, sizeof(VID_SSH_IPSEC_EXPRESS_1_1_1), "Ssh Communications Security IPSEC Express version 1.1.1" },
   { VID_SSH_IPSEC_EXPRESS_1_1_2, sizeof(VID_SSH_IPSEC_EXPRESS_1_1_2), "Ssh Communications Security IPSEC Express version 1.1.2" },
@@ -2941,50 +2932,6 @@ static const byte_string vendor_id[] = {
 };
 
 
-/* Tries to match val against each element in the value_string array vs.
-   Returns the associated string ptr, and sets "*idx" to the index in
-   that table, on a match, and returns NULL, and sets "*idx" to -1,
-   on failure. */
-static const gchar*
-match_strbyte_idx(const guint8 *val, const gint val_len, const byte_string *vs, gint *idx) {
-  gint i = 0;
-
-  if (vs) {
-    while (vs[i].strptr) {
-      if (val_len >= vs[i].len && !memcmp(vs[i].value, val, vs[i].len)) {
-        *idx = i;
-        return(vs[i].strptr);
-      }
-      i++;
-    }
-  }
-
-  *idx = -1;
-  return NULL;
-}
-/* Like match_strbyte_idx(), but doesn't return the index. */
-static const gchar*
-match_strbyte(const guint8 *val,const gint val_len, const byte_string *vs) {
-  gint ignore_me;
-  return match_strbyte_idx(val, val_len, vs, &ignore_me);
-}
-
-/* Tries to match val against each element in the value_string array vs.
-   Returns the associated string ptr on a match.
-   Formats val with fmt, and returns the resulting string, on failure. */
-static const gchar*
-byte_to_str(const guint8 *val,const gint val_len, const byte_string *vs, const char *fmt) {
-  const gchar *ret;
-
-  DISSECTOR_ASSERT(fmt != NULL);
-  ret = match_strbyte(val, val_len, vs);
-  if (ret != NULL)
-    return ret;
-
-  return wmem_strdup_printf(wmem_packet_scope(), fmt, val);
-}
-
-
 
 static void
 dissect_payloads(tvbuff_t *tvb, proto_tree *tree,
@@ -4777,7 +4724,7 @@ dissect_vid(tvbuff_t *tvb, int offset, int length, proto_tree *tree)
 
   pVID = tvb_get_ptr(tvb, offset, length);
 
-  vendorstring = byte_to_str(pVID, (gint)length, vendor_id, "Unknown Vendor ID");
+  vendorstring = bytesprefix_to_str(pVID, (size_t)length, vendor_id, "Unknown Vendor ID");
   proto_tree_add_item(tree, hf_isakmp_vid_bytes, tvb, offset, length, ENC_NA);
   proto_tree_add_string(tree, hf_isakmp_vid_string, tvb, offset, length, vendorstring);
   proto_item_append_text(tree," : %s", vendorstring);
diff --git a/epan/value_string.c b/epan/value_string.c
index c6aafbcfd4..858a6d25fd 100644
--- a/epan/value_string.c
+++ b/epan/value_string.c
@@ -641,6 +641,83 @@ try_rval64_to_str(const guint64 val, const range_string *rs)
     return try_rval64_to_str_idx(val, rs, &ignore_me);
 }
 
+
+/* BYTE BUFFER TO STRING MATCHING */
+
+/* Like val_to_str except for bytes_string */
+const gchar *
+bytesval_to_str(const guint8 *val, const size_t val_len, const bytes_string *bs, const char *fmt)
+{
+    const gchar *ret;
+
+    DISSECTOR_ASSERT(fmt != NULL);
+
+    ret = try_bytesval_to_str(val, val_len, bs);
+    if (ret != NULL)
+        return ret;
+
+    /*
+     * XXX should this use bytes_to_str as format parameter for consistency?
+     * Though for bytes I guess most of the time you want to show "Unknown"
+     * anyway rather than "Unknown (\x13\x37...)"
+     */
+    return wmem_strdup(wmem_packet_scope(), fmt);
+}
+
+/* Like try_val_to_str except for bytes_string */
+const gchar *
+try_bytesval_to_str(const guint8 *val, const size_t val_len, const bytes_string *bs)
+{
+    guint i = 0;
+
+    if (bs) {
+        while (bs[i].strptr) {
+            if (bs[i].value_length == val_len && !memcmp(bs[i].value, val, val_len)) {
+                return bs[i].strptr;
+            }
+            i++;
+        }
+    }
+
+    return NULL;
+}
+
+/* Like val_to_str, but tries to find a prefix (instead of an exact) match
+   against any element of the bytes_string array bs. */
+const gchar *
+bytesprefix_to_str(const guint8 *prefix, const size_t prefix_len, const bytes_string *bs, const char *fmt)
+{
+    const gchar *ret;
+
+    DISSECTOR_ASSERT(fmt != NULL);
+
+    ret = try_bytesprefix_to_str(prefix, prefix_len, bs);
+    if (ret != NULL)
+        return ret;
+
+    /* XXX See note at bytesval_to_str. */
+    return wmem_strdup(wmem_packet_scope(), fmt);
+}
+
+/* Like try_val_to_str, but tries to find a prefix (instead of an exact) match
+   against any element of the bytes_string array bs. */
+const gchar *
+try_bytesprefix_to_str(const guint8 *prefix, const size_t prefix_len, const bytes_string *bs)
+{
+    guint i = 0;
+
+    if (bs) {
+        while (bs[i].strptr) {
+            if (prefix_len >= bs[i].value_length && !memcmp(bs[i].value, prefix, prefix_len)) {
+                return bs[i].strptr;
+            }
+            i++;
+        }
+    }
+
+    return NULL;
+}
+
 /* MISC */
 
 /* Functions for use by proto_registrar_dump_values(), see proto.c */
diff --git a/epan/value_string.h b/epan/value_string.h
index 90b40f51b0..92d24deb97 100644
--- a/epan/value_string.h
+++ b/epan/value_string.h
@@ -274,6 +274,32 @@ WS_DLL_PUBLIC
 const gchar *
 try_rval64_to_str_idx(const guint64 val, const range_string *rs, gint *idx);
 
+/* BYTES TO STRING MATCHING */
+
+typedef struct _bytes_string {
+  const guint8 *value;
+  const size_t  value_length;
+  const gchar  *strptr;
+} bytes_string;
+
+WS_DLL_PUBLIC
+const gchar *
+bytesval_to_str(const guint8 *val, const size_t val_len, const bytes_string *bs, const char *fmt)
+G_GNUC_PRINTF(4, 0);
+
+WS_DLL_PUBLIC
+const gchar *
+try_bytesval_to_str(const guint8 *val, const size_t val_len, const bytes_string *bs);
+
+WS_DLL_PUBLIC
+const gchar *
+bytesprefix_to_str(const guint8 *prefix, const size_t prefix_len, const bytes_string *bs, const char *fmt)
+G_GNUC_PRINTF(4, 0);
+
+WS_DLL_PUBLIC
+const gchar *
+try_bytesprefix_to_str(const guint8 *prefix, const size_t prefix_len, const bytes_string *bs);
+
 /* MISC (generally do not use) */
 
 WS_DLL_LOCAL